Suspension fork having reserved arch

ABSTRACT

A front suspension fork for cycles includes an inverted U-shaped reversed arch having downwardly extending legs that are integral with the upper ends of the outer sections of the telescopic fork, thereby to define a rigid unitary slider component fork. The reversed arch is inclined rearwardly at an acute angle relative to the vertical plane of the fork. Strengthening mass portions extend forwardly from the lower ends of the arch between the inner fork sections, thereby to increase the rigidity of the slider component without interfering with brake operation.

FIELD OF THE INVENTION

[0001] A suspension fork for bicycles and motorcycles includes areversed arch that is integrally connected between the upper ends of theouter telescopic leg sections of the fork. The reversed arch is inclinedrearwardly of the fork, thereby to reduce the possibility ofinterference with the brake means of the cycle.

BACKGROUND OF THE INVENTION

[0002] Brief Description of the Prior Art

[0003] Front suspension forks for cycles such as bicycles andmotorcycles are well known in the prior art, as evidenced by the patentsto Turner U.S. Pat. Nos. Des. 401,537 and 4,971,344, and Boyer, et al.,U.S. Pat. No. 5,653,007. In such known suspension forks, the verticalleg portions of the fork comprise a pair of telescopic tubular sectionsthe inner ones of which are connected at their upper ends with ahorizontal crown that is connected intermediate its ends with thehandlebar steerer rod or shaft. The outer fork sections (i.e., the“sliders”) are connected at their upper ends by a transversely extendingarch, thereby to define a unitary slider component the lower ends ofwhich are connected with opposite ends of the wheel axle. Shock absorbermeans are provided that include a compression spring that biases thesections apart, and damper means are provided for dampening forkvibrations.

[0004] As shown by the aforementioned Turner utility patent, the forksliders initially consisted of three or more pieces bolted together. Thearch was the piece that tied the right and left sliders together so theymoved in tandem. Early technology and manufacturing techniques yieldedforks that were very flexible. To fight the flex problem and reducehardware proliferation, the cantilever pivot bolts were also used toanchor the arch to the sliders. Since cantilever rim brakes aregenerally mounted on the front of the fork, the arch was also mounted onthe front. As fork designs and technology progressed, the sliders becameincreasingly integrated. Eventually, as shown by the Boyer, et al.,patent, the sliders were bonded instead of bolted together, thereby todefine a unitary slider component. This relieved the arch of itsprevious duties, but it remained on the front nonetheless. Finally, asshown by the Turner design patent, the sliders were cast as one piece.

[0005] In these known suspension forks, the wheel brake operating meansare generally mounted forwardly of the suspension fork, and the archsimilarly extends between the forward portions of the upper ends of theouter concentrically arranged fork section. Consequently, these forkshave the disadvantage that the arch connection between the fork legouter sections cannot be optimized for strength without interfering withthe brake operation and design of the brake means.

[0006] Pace Cycles Limited of York, England, has proposed suspensionforks that include arches that are clamped or bolted to the front and/orrear surfaces of the outer tubular sections of the suspension fork. Inthe Pace RC-35 suspension fork that was offered for sale in 1993, aseparate arch component was clamped onto the rear side of the fork, aswere the brake means. In the Pace forks, the arches and the brake meanswere mounted on the same side of the fork, whereby the arches interfereto some extent with the operation of the brake means, since as withother designs, the brake means are coincident with the arch.

[0007] The present invention was developed to avoid the above and otherdrawbacks of the suspension forks of the prior art. During itsdevelopment of its one-piece cast sliders, Applicant discovered that thegreatest increase in stiffness resulted when the arch was ‘wrapped’ andthickened around the inside of the sliders, but the amount of wrap andthe thickness of the possible material was limited. This was due to thefact that the additional wrap meant and material greater mass, and thisgreater mass interfered with the operation of the cantilever brakes. Areduced opening made wheel installation and removal of the wheeldifficult or impossible. In the end, the state-of the-art sliders were acompromise between optimal stiffness on the one hand, and ease of wheelinstallation and removal on the other hand.

SUMMARY OF THE INVENTION

[0008] Accordingly, a primary object of the present invention is toprovide a suspension fork in which the arch means for connecting thefork leg outer section are inclined rearwardly at an acute anglerelative to the vertical plane of the fork. In this manner, thereversely inclined arch does not interfere with the operation of thebrake means arranged forwardly or rearwardly of the fork.

[0009] According to another feature of the invention, in order to obtaina higher stiffness to weight ratio, each of the lower ends of theinverted U-shaped arch includes a stiffening wrap mass that extendsbetween the lower leg portions of the arch and the adjacent upperportions of the respective outer fork sections, without negativelyaffecting operation of the brake means. The resulting increase of thetorsional stiffness of the sliders reduces binding of the slidersrelative to the stanchions over which they slide during the suspensionmovement, thereby offering a smoother ride. The arch may be nearly{fraction (1/2)} inch shorter, owing to its relative position behind theaxle of the wheel, whereby the shorter arch is stiffer and lighter aswell.

[0010] According to a further object of the invention as applied to afork using cantilevered rim brake means, the brake posts extendforwardly of the fork and are arranged off-center in the direction ofeach other. The brake posts are reduced in height, since the brake armsno longer must clear a front-mounted arch. This permits the brakes to bearranged closer to the centerline of the fork, thereby decreasing theirtwisting leverage over the outer fork sections. This results incantilever braking with improved modulation and power.

[0011] A further object of the invention is to provide a suspension forkfor use with disc brake means wherein the slider member includes arearwardly inclined arch connected between the upper ends of the lowersections, and disc brake mounting posts arranged at the lower rear endof one of the lower leg sections, thereby to provide a rigid sliderunit.

[0012] According to another object of the invention, the rearwardlyinclined reversed arch shields the seals of the fork against dirt anddebris produced by rotation of the associated tire. The reversed archconstruction affords improved slider torsional stiffness, reduction inslider weight, and protection of the fork seals.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other objects and advantages of the invention will becomeapparent from a study of the following specification when viewed in thelight of the accompanying drawings, in which:

[0014]FIGS. 1 and 2 are front and left hand side views, respectively, ofthe improved suspension fork of the present invention as used inconnection with rim brake means;

[0015]FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

[0016] FIGS. 4-7 are front, right hand side, top, and bottom views ofthe rigid slider component defined by the integral arch and outer legsections;

[0017] FIGS. 8-10 illustrate the manner of mounting cantilever brakemeans on the forwardly extending brake posts of the slider component;

[0018]FIGS. 11 and 12 are front and right hand views of the improvedfork as used with disc brake means; and

[0019] FIGS. 13-15 are front elevation, right elevation, and top planviews, respectively, of the slider component of the fork of FIGS. 11 and12.

DETAILED DESCRIPTION

[0020] Referring first more particularly to FIGS. 1 and 2, the improvedreversed arch suspension fork 2 includes a horizontal crown portion 4and a pair of downwardly depending leg portions 6 and 8. As is known inthe art, the leg portions are telescopic and include a pair of outertubular sections 6 a and 8 a arranged concentrically about a pair ofinner leg sections 6 b and 8 b, respectively. The outer and innersections are arranged for relative longitudinal sliding displacement,flexible tubular seal means 10 being provided for sealing the gapbetween the upper end of the outer sections 6 a and 8 a and the adjacentcircumferential surfaces of the inner sections 6 b and 8 b. Intermediateits ends, the crown portion 4 carries the vertically upwardly extendingsteerer rod 12 that supports the handlebar steering means (not shown).

[0021] In accordance with the present invention, the outer fork sections6 a and 8 a are connected at their upper ends by an integral invertedU-shaped reversed arch portion 14 having leg portions 14 a and 14 b thatare integral with the upper ends of the outer section 6 a and 8 a,respectively, thereby to define a rigid unitary slider component 15(FIGS. 8-10). As best shown in FIG. 2, in accordance with acharacterizing feature of the invention, the reverse arch 14 is inclinedrearwardly of the fork by the acute angle ∝ relative to the verticalaxis of the fork. At its upper end, the reverse arch 14 includes arearwardly projecting flange 14 c that protects the cycle frame and thecycle operator from the mud and debris that is thrown upwardly by thecycle front wheel 20.

[0022] Extending forwardly from the outer fork sections 6 a and 8 a area pair of brake posts 22 and 24 that pivotally support the brake arms 26and 28 that carry brake shoes 30 and 32, respectively. At their lowerends, the outer fork sections include forwardly extending integralsupport portions 6 c and 8 c having downwardly extending slots forreceiving the ends of the wheel axle 36. Rotatably supported on the axle36 is the wheel hub 38 having radially extending spokes 40 that supportthe wheel rim 42 on which is mounted the resilient tire 44. The brakeshoes 30 and 32 are displaced into braking engagement with the wheel rim42 by the brake cables 46 that are manually operable by the brakeoperating means 48, as is known in the art.

[0023] Referring now to FIG. 3, the hollow fork leg 8 contains theconventional shock absorbing means including the compression spring 50,and the fork leg 6 contains the conventional fluid damping means 52. Aswill be described in greater detail below, in accordance with anotherimportant feature of the invention, the adjacent portions of the lowerextremities of the reverse arch leg portions and the upper ends of theouter sections 8 a and 8 b, respectively, merge into thickenedwrap-around strengthening masses 14 d. These strengthening wrap-aroundmasses provide torsional stability to the slider fork component 15. Asshown in FIG. 1, the brake support posts 22 and 24 are displaced by thedistance “a” inwardly toward each other from the vertical transversecenter lines of the leg portions of the fork. Since the brake posts 22and 24 extend forwardly of the fork, and since the reverse arch portion14 is inclined rearwardly of the fork, the arch 14 presents nointerference with the operation of the brake operating cables 46, andaccordingly, the brake posts may be shorter than masses provide usedwith cantilevered type brakes. Furthermore, by mounting the brake posts22 and 24 on the wrapped around strengthening mass portions 15 a and 15b of the reverse arch and the upper ends of the outer sections, a morestabilized and positive braking operation is achieved.

[0024] Referring to FIGS. 4-7, it will be seen that the cast integrallower ends of the arch leg portions 14 a and 14 b include wrap-aroundstrengthening mass portions 14 that extend inwardly between the innerfork sections 6 b and 8 b, respectively. These wrap-around mass portionsmerge with inwardly thickened portions 6 d and 8 d that extend inwardlyfrom the adjacent upper end surfaces of the outer fork sections 6 a and8 a, respectively. The upper extremities of the outer sections 6 a and 8a terminate in horizontal annular shelves or ledges 9 that support theflexible annular seals 10 of FIG. 1 within recesses 14 e (FIGS. 8 and 9)contained within the lower ends of the arch leg portions.

[0025] As shown in FIG. 4, the forwardly extending brake posts 22 and 24are arranged adjacent each other at the thickened upper end portions 6 dand 8 d of the outer fork sections 6 a and 8 a, respectively. Referringto FIGS. 8-10, cantilevered brake arms 60 and 62 are pivotally mountedon the brake posts 22 and 24, respectively, said brake arms carryingbrake shoes 64 and 66 arranged for braking engagement with the wheelrim, now shown. The cantilevered brake arms are pivoted toward thebraking positions by the brake cable 68 of the cantilever brakeoperating means 70, as is know in the art.

[0026] Thus, the wrap around arch portions 14 d and the thickened upperend portions 6 d and 8 d of the outer fork sections 6 a and 8 a serve tostrengthen the torsional stability of the unitary lower fork componentthat carries both the wheel axle 36 and the brake arm means 26, 28 (ofFIG. 1) and 60, 62 (of FIG. 8).

[0027] Referring now to the disc brake embodiment of the invention shownin FIGS. 11-15, the front fork 102 includes a crown 104 connectedbetween the upper ends of the upper sections 106 b and 108 b of the forklegs 106 and 108. The reverse arch 114 is connected between the upperends of the lower leg sections 106 a and 108 a, thereby to define therigid lower slider unit 115 shown in FIGS. 13-15. The wheel and hubassembly 139 including a brake disk 133 is mounted between the forwardlyextending integral mounting portions 106 c and 108 c at the lower endsof the lower leg sections. The disc brake operating means 129 is boltedtoo the rear of the fork for operation by the hand-grip operating means148, as is known in the art.

[0028] As best shown in FIGS. 11 and 13, the suspension fork includesstrengthening masses 114 d that extend from the reverse arch portion 114between the upper ends of the lower fork sections 106 a and 106 b. Theledges 109 support the bellows seals 110 of FIG. 11. The resultant forksuspension fork 102 thus has a rigid compact construction withstrengthening masses provided between the upper ends of the lowersections without any interference with brake operation, or with theremoval of the front wheel from the fork.

[0029] While in accordance with the provisions of the Patent Statutesthe preferred forms and embodiments of the invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes may be made without deviating from theinventive concepts set forth above.

What is claimed is:
 1. A reversed arch front suspension fork assemblyfor cycles having a front wheel rotatably mounted on an axle, and brakemeans for braking the front wheel, comprising: a vertical generallyU-shaped inverted suspension fork having front and rear sides, said forkincluding: (a) a horizontal crown portion having a pair of ends; (b) apair of vertical sectional telescopic leg portions extending downwardlyfrom said crown portion ends, respectively, each of said fork legportions including: (1) an inner upper tubular fork section having anupper end connected with the associated end of said crown portion; and(2) an outer lower tubular fork section slidably mounted concentricallyabout said inner fork section, said outer fork section having upper andlower ends, said outer fork section including axle connecting meansintegral with the lower end of said outer fork section for connectingone end of the front wheel axle with said outer fork section; (c) agenerally vertical reversed arch portion integral with and connectedbetween the upper ends of said leg sections to define a unitary rigidslider component, said reversed arch portion having an invertedgenerally U-shaped configuration defining a pair of downwardly extendingleg portions the lower ends of which are integral with the upper ends ofsaid outer fork sections, respectively, said reversed arch portion beinginclined rearwardly at an acute angle relative to the vertical planecontaining said fork; and (d) brake connecting means for connectingfront wheel brake means with said rigid slider component.
 2. A reversedarch suspension fork assembly as defined in claim 1, wherein saidreversed arch legs include at their lower extremities strengtheningwrapped mass end portions that extend forwardly between said inner forksections, respectively, thereby to increase the torsional stiffness ofthe fork.
 3. A reversed arch suspension fork assembly as defined inclaim 2, wherein said axle connecting means include integral portionsthat extend forwardly from the lower ends of said outer fork sections,respectively, said integral connecting portions containing opposed slotsfor receiving the ends of the front wheel axle, respectively.
 4. Areversed arch suspension fork assembly as defined in claim 3, andfurther including: (e) shock absorber means connected between thesections of one of said fork leg portions, said shock absorber meansincluding a helical compression spring arranged concentrically withinsaid one fork leg for biasing the sections thereof axially apart; (f)dampening means arranged in the other of said fork leg portions fordampening the relative movement between the sections of said front forkleg portions; and (g) a pair of flexible bellows-type annular sealsmounted concentrically about the upper ends of said outer fork sections,respectively, said seals extending upwardly concentrically about and insliding engagement with the outer circumferential surfaces of said innerfork sections, thereby to seal the gap between the upper end of saidouter fork sections and the adjacent circumferential surface of saidinner fork sections, respectively.
 5. A reversed arch suspension forkassembly as defined in claim 4, wherein said reversed arch strengtheningwrapped mass end portions contain recesses for receiving the lower endsof said annular seals, respectively.
 6. A reversed arch suspension forkassembly as defined in claim 3, and further including: (e) disc brakemeans connected with said brake connecting means.
 7. A reversed archsuspension fork assembly as defined in claim 6, wherein said brakeconnecting means includes a plurality of vertically spaced connectingportions arranged on the rear side of the lower end of one of said lowersections.
 8. A reversed arch suspension assembly as defined in claim 7,and further including: (f) a front wheel assembly including: (1) an axlemounted between said axle connecting means; (2) a hub rotatably mountedconcentrically about said axle; (3) an annular metal rim supported bysaid hub; (4) a resilient tire mounted concentrically about said rim;and (5) an annular brake disk connected with said hub for rotation aboutsaid axle.
 9. A reversed arch assembly as defined in claim 3, andfurther including: (e) cantilevered rim brake means connected with saidbrake connecting means.
 10. A reversed arch assembly as defined in claim9, wherein said brake connecting means includes a pair of brake postsextending forwardly of the upper ends of said fork lower sections,respectively, said cantilevered rim brake means being arranged on saidbrake posts forwardly of said fork.
 11. A reversed arch suspension forkassembly as defined in claim 10, and further including: (f) a frontwheel assembly having: (1) an axle mounted between said axle connectingmeans of said outer fork sections; (2) a hub rotatably mountedconcentrically on said axle; (3) an annular metal rim supported by saidhub; and (4) a resilient tire mounted concentrically about said rim; (5)said brake means including brake pads arranged for engagement withopposite sides of said rim.
 12. A reversed arch suspension fork assemblyas defined in claim 11, wherein said brake posts are arranged adjacentthe lower extremities of said reversed arch strengthening wrapped massend portions, said brake posts being arranged off-center toward eachother relative to the vertical planes that pass through the longitudinalaxes of the fork leg portions normal to the plane of the fork,respectively.